Within a decade, most of today's synthetic performance-enhancing drugs - from anabolic steroids to erythropoietin - may be all but abandoned in favor of a far more effective strategy: gene doping.

Further, gene doping, a science that would render current tests irrelevant, looms on the horizon.

He wrote that in addition to overall muscle enlargement, gene doping could be used to tweak genes to convert muscle fibres to the fast type for sprinters and to those with greater endurance for marathon runners.